tf::StaticTaskLike Concept Reference

determines if a callable is a static task More...

#include <taskflow/core/task.hpp>

Concept definition

template<typename C>
concept tf::StaticTaskLike =  std::invocable<C> &&
                     std::same_as<std::invoke_result_t<C>, void>

Detailed Description

determines if a callable is a static task

A static task is a callable object that takes no arguments and returns void. It is constructible from std::function<void()>.

Requirements

• Must be invocable with no arguments
• Must return void

Examples

// Valid static tasks (satisfy StaticTaskLike)
 
// Simple lambda capturing nothing
auto static_task1 = []() {};
static_assert(StaticTaskLike<decltype(static_task1)>);
 
// Lambda capturing variables
int x = 10;
auto static_task2 = [x]() { std::cout << x << '\n'; };
static_assert(StaticTaskLike<decltype(static_task2)>);
 
// Function object (functor)
struct SimpleTask {
  void operator()() const { std::cout << "task\n"; }
};
static_assert(StaticTaskLike<SimpleTask>);
 
// Free function
void my_task() { std::cout << "free function task\n"; }
static_assert(StaticTaskLike<decltype(&my_task)>);
 
// Use in taskflow
tf::Taskflow taskflow;
auto task = taskflow.emplace(static_task1).name("static");

Invalid Examples

// Invalid: takes parameters
auto task_with_param = [](int a) { std::cout << a << '\n'; };
// static_assert(StaticTaskLike<decltype(task_with_param)>);  // FAILS
 
// Invalid: returns non-void
auto task_returns_int = []() { return 42; };
// static_assert(StaticTaskLike<decltype(task_returns_int)>);  // FAILS